NCERT Environmental Studies (EVS) important notes Part 19 for AEES, KVS, NVS, DSSSB, UPTET, REET, CTET, BTET, MPTET, HTET and All other Teaching Exams
NCERT
Environmental Studies
Important Notes
Part 19
- Ninety per cent of the world population occupies only thirty per cent of land area. The remaining seventy per cent of the land is either sparsely populated or uninhabited.
- Land is among the most important natural resources. It covers only about thirty per cent of the total area of the earth’s surface and all parts of this small percentage are not habitable.
- The uneven distribution of population in different parts of the world is mainly due to varied characteristics of land and climate. The rugged topography, steep slopes of the mountains, low-lying areas susceptible to water logging, desert areas, thick forested areas are normally sparsely populated or uninhabited. Plains and river valleys offer suitable land for agriculture. Hence, these are the densely populated areas of the world.
- Land is used for different purposes such as agriculture, forestry, mining, building houses, roads and setting up of industries. This is commonly termed as Land use.
- he use of land is determined by physical factors such as topography, soil, climate, minerals and availability of water. Human factors such as population and technology are also important determinants of land use pattern.
- Land can also be divided on the basis of private land and community land. Private land is owned by individuals whereas, community land is owned by the community for common uses like collection of fodder, fruits, nuts or medicinal herbs. These community lands are also called common property resources.
- Land degradation, landslides, soil erosion, desertification are the major threats to the environment because of the expansion of agriculture and constructional activities.
- Afforestation, land reclamation, regulated use of chemical pesticide and fertilisers and checks on overgrazing are some of the common methods used to conserve land.
- Landslides are simply defined as the mass movement of rock, debris or earth down a slope. They often take place in conjunction with earthquakes, floods and volcanoes.
- A prolonged spell of rainfall can cause heavy landslide that can block the flow of river for quite some time.
- The formation of river blocks can cause havoc to the settlements downstream on its bursting. In the hilly terrain landslides have been a major and widely spread natural disaster that often strike life and property and occupy a position of major concern.
Some broad mitigation techniques of landslide are as follows:
• Hazard mapping locate areas prone to landslides. Hence, such areas can be avoided for building settlements.
• Construction of retention wall to stop land from slipping.
• Increase in the vegetation cover is an effective way to arrest landslide.
• The surface drainage control works are implemented to control the movement of landslide along with rain water and spring flows.
SOIL
- The thin layer of grainy substance covering the surface of the earth is called soil. It is closely linked to land.
- Landforms determine the type of soil.
- Soil is made up of organic matter, minerals and weathered rocks found on the earth. This happens through the process of weathering.
- The right mix of minerals and organic matter make the soil fertile.
- In India soils could be alluvial, black, red, laterite, desertic and mountain soil.
- Weathering
The breaking up and decay of exposed rocks, by temperature changes, frost action, plants, animals and man.
FACTORS OF SOIL FORMATION
The major factors of soil formation are the nature of the parent rock and climatic factors. Other factors are the topography, role of organic material and time taken for the composition of soil formation. All these differ from place to place.
DEGRADATION OF SOIL AND CONSERVATION MEASURES
Soil erosion and depletion are the major threats to soil as a resource. Both human and natural factors can lead to degradation of soils. Factors which lead to soil degradation are deforestation, overgrazing, overuse of chemical feritilisers or pesticides, rain wash, landslides and floods.
Methods of Soil Conservation
Mulching: The bare ground between plants is covered with a layer of organic matter like straw. It helps to retain soil moisture.
Contour barriers: Stones, grass, soil are used to build barriers along contours. Trenches are made in front of the barriers to collect water.
Rock dam: Rocks are piled up to slow down the flow of water. This prevents gullies and further soil loss.
Terrace farming: These are made on the steep slopes so that flat surfaces are available to grow crops. They can reduce surface run-off and soil erosion.
Intercropping: Different crops are grown in alternate rows and are sown at different times to protect the soil from rain wash.
Contour ploughing: Ploughing parallel to the contours of a hill slope to form a natural barrier for water to flow down the slope.
Shelter belts: In the coastal and dry regions, rows of trees are planted to check the wind movement to protect soil cover.
WATER
- Water is a vital renewable natural resource.
- Three-fourth’s of the earth’s surface is covered with water. It is therefore appropriately called the ‘water planet’. It was in the primitive oceans that life began almost 3.5 billion years back.
- Even today, the oceans cover two-thirds of the earth’s surface and support a rich variety of plant and animal life. The ocean water is however saline and not fit for human consumption.
- Fresh water accounts for only about 2.7 per cent. Nearly 70 per cent of this occurs as ice sheets and glaciers in Antarctica, Greenland and mountain regions. Due to their location they are inaccessible. Only 1 per cent of freshwater is available and fit for human use. It is found as ground water, as surface water in rivers and lakes and as water vapour in the atmosphere. Fresh water is therefore, the most precious substance on earth.
- Water can neither be added nor subtracted from the earth. Its total volume remains constant. Its abundance only seems to vary because it is in constant motion, cycling through the oceans, the air, the land and back again, through the processes of evaporation, precipitation and run-off. This as you already know is referred to as the ‘water cycle’.
- Humans use huge amounts of water not only for drinking and washing but also in the process of production. Water for agriculture, industries, generating electricity through reservoirs of dams are the other usages.
- Increasing population, rising demands for food and cash crops, increasing urbanisation and rising standards of living are the major factors leading to shortages in supply of fresh water either due to drying up of water sources or water pollution.
- In 1975, the consumption of water for human use was 3850cu km/year. It soared to more than 6000 cu km/year in the year 2000.
- A dripping tap wastes 1200 litres in a year.
- An average urban Indian uses about 135 litres of water every day.
- Amreli city in Saurastra region with a population of 1.25 lakhs is completely dependent on purchasing water from the nearby talukas.
PROBLEMS OF WATER AVAILABILITY
There is scarcity of water in many regions of the world. Most of Africa, West Asia, South Asia, parts of western USA, north-west Mexico, parts of South America and entire Australia are facing shortages in fresh water supply. Countries located in climatic zones most susceptible to droughts face great problems of water scarcity. Thus, water shortage may be a consequence of variation in seasonal or annual precipitation or the scarcity is caused by over-exploitation and contamination of water sources.
CONSERVATION OF WATER RESOURCES
- Access to clean and adequate water sources is a major problem facing the world today. Steps have to be taken to conserve this dwindling resource. Even though water is a renewable resource, its overuse and pollution make it unfit for use.
- Discharge of untreated or partially treated sewage, agricultural chemicals and industrial effluents in water bodies are major contaminants. They pollute water with nitrates, metals and pesticides.
- Most of these chemicals being non-biodegradable reach human bodies through water. Water pollution can be controlled by treating these effluents suitably before releasing them in water bodies.
- Forest and other vegetation cover slow the surface runoff and replenish underground water.
- Water harvesting is another method to save surface runoff. Water is used for irrigating fields.
- The canals should be properly lined to minimise losses by water seepage.
- Sprinklers effectively irrigate the area by checking water losses through seepage and evaporation.
- In dry regions with high rates of evaporation, drip or trickle irrigation is very useful. The valuable water resource can therefore be conserved by adopting these means of conservation.
- Rain water harvesting is the process of collecting rain water from roof tops and directing it to an appropriate location and storing if for future use. On an average, one spell of rain for two hours is enough to save 8,000 litres of water.
NATURAL VEGETATION AND WILDLIFE
- Natural vegetation and wildlife exist only in the narrow zone of contact between the lithosphere, hydrosphere and atmosphere that we call biosphere.
- In the biosphere living beings are inter-related and interdependent on each other for survival. This life supporting system is known as the ecosystem.
- Vegetation and wildlife are valuable resources.
- Plants provide us with timber, give shelter to animals, produce oxygen we breathe, protects soils so essential for growing crops, act as shelter belts, help in storage of underground water, give us fruits, nuts, latex, turpentine oil, gum, medicinal plants and also the paper that is so essential for your studies.
- There are innumerable uses of plants and you can add some more.
- Wildlife includes animals, birds, insects as well as the aquatic life forms. They provide us milk, meat, hides and wool.
- Insects like bees provide us honey, help in pollination of flowers and have an important role to play as decomposers in the ecosystem.
- The birds feed on insects and act as decomposers as well. Vulture due to its ability to feed on dead livestock is a scavenger and considered a vital cleanser of the environment. So animals big or small, all are integral to maintaining balance in the ecosystem.
- Brahma Kamal a Medicinal Herb.
DISTRIBUTION OF NATURAL VEGETATION
- The growth of vegetation depends primarily on temperature and moisture.
- The major vegetation types of the world are grouped as forests, grasslands, scrubs and tundra.
- In areas of heavy rainfall, huge trees may thrive. The forests are thus associated with areas having abundant water supply. As the amount of moisture decreases the size of trees and their density reduces.
- In the regions of moderate rainfall short stunted trees and grasses grow forming the grasslands of the world.
- In dry areas of low rainfall, thorny shrubs and scrubs grow. In such areas plants have deep roots and leaves have thorny and waxy surface to reduce loss of moisture by transpiration. Tundra vegetation of cold Polar Regions comprise of mosses and lichens.
- Forests are broadly classified as evergreen and deciduous depending on when they shed their leaves.
- Evergreen forests do not shed their leaves simultaneously in any season of the year.
- Deciduous forests shed their leaves in a particular season to conserve loss of moisture through transpiration. These forests are further classified as tropical or temperate based on their location in different latitudes.
- Today there are many more people in the world than there were two centuries back. To feed the growing numbers, large areas of forests have been cleared to grow crops. Forest cover all over the world is vanishing rapidly. There is an urgent need to conserve this valuable resource.
CONSERVATION OF NATURAL
VEGETATION AND WILDLIFE
VEGETATION AND WILDLIFE
- Forests are our wealth. Plants give shelter to the animals and together they maintain the ecosystem. Changes of climate and human interferences can cause the loss of natural habitats for the plants and animals. Many species have become vulnerable or endangered and some are on the verge of extinction.
- Deforestation, soil erosion, constructional activities, forest fires, tsunami and landslides are some of the human made and natural factors which together accelerate the process of extinction of these great natural resources.
- One of the major concerns is the increasing incidents of poaching that result in a sharp decline in the number of particular species.
- The animals are poached for collection and illegal trade of hides, skins, nails, teeth, horns as well as feathers. Some of these animals are tiger, lion, elephant, deer, black buck, crocodile, rhinoceros, snow leopard, ostrich and peacock. These can be conserved by increasing awareness.
- National parks, wildlife sanctuaries, biosphere reserves are made to protect our natural vegetation and wildlife. Conservation of creeks, lakes, and wetlands is necessary to save the precious resource from depletion.
- There is a balance in the environment if the relative number of species is not disturbed. Human activities in several parts of the world have disturbed the natural habitats of many species. Due to indiscriminate killings, several birds and animals have either become extinct or are on the verge of extinction.
- Awareness programmes like social forestry and Vanamohatasava should be encouraged at the regional and community level. School children should be encouraged for bird watching and visiting nature camps so that they appreciate the habitat of varied species.
- Many countries have passed laws declaring that the trades as well as killing of birds and animals are illegal. In India, killing of lions, tigers, deers, great Indian bustards and peacocks have been banned.
- An international convention CITES has been established that lists several species of animals and birds inwhich trade is prohibited. Conservation of plants and animals is an ethical duty of every citizen.
- National Park
A natural area designated to protect the ecological integrity of one or more ecosystems for present and future generations. - Biosphere reserves Series of protected areas linked through a global network, intended to demonstrate the relationship between conservation and development.
- CITIES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an international agreement between governments. It aims to ensure that international trade in specimens of wild animals and plants does not threaten their survival. Roughly 5,000 species of animals and 28,000 species of plants are protected. Bears, dolphins, cacti,corals, orchids and aloes are some examples.
Questions and Answers
Ques 1 Which one of the following is NOT a factor of soil formation?
(a) time
(b) soil texture
(c) organic matter
Ans- (b) soil texture
Ques 2 Which one of the following methods is most appropriate to check soil erosion on steep slopes?
(a) shelter belts
(b) mulching
(c) terrace cultivation
Ans- (c) terrace cultivation
Ques 3 Which one of the following is NOT in favour of the conservation of nature?
(a) switch off the bulb when not in use
(b) close the tap immediately after using
(c) dispose polypacks after shopping
Ans- (c) dispose polypacks after shopping
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#NCERT Environmental Studies (EVS) important notes Part 19 for AEES, KVS, NVS, DSSSB, UPTET, REET, CTET, BTET, MPTET, HTET and All other Teaching Exams